Add Monorepo Merge Notice Workflow (#12101)

Added Merge Notice Workflow

.github/workflows/monorepo-merge-notices.yml

@@ -0,0 +1,33 @@
+name: 'Monorepo Merge Notices'
+on:
+  pull_request_target:
+    types: [ 'opened' ]
+  issues:
+    types: [ 'opened' ]
+jobs:
+  issue_block:
+    name: 'Block Issues & Pull Requests'
+    runs-on: 'ubuntu-latest'
+    steps:
+      - name: 'Add Merge Notice'
+        uses: 'actions/github-script@v7'
+        with:
+          script: |
+              github.rest.issues.createComment( {
+                issue_number: context.issue.number,
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                body: 'Thank you for your interest in contributing to WooCommerce!\n\n\
+                WooCommerce Blocks [has been merged into the WooCommerce Monorepo](https://developer.woo.com/2023/12/01/woocommerce-blocks-merging-into-the-woocommerce-monorepo/).\n\n\
+                From now on, please open any issues or pull requests in the [woocommerce/woocommerce](https://github.com/woocommerce/woocommerce) repository.'
+              } );
+      - name: 'Close'
+        uses: 'actions/github-script@v7'
+        with:
+          script: |
+            github.rest.issues.update({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              state: 'closed'
+            });